This application claims priority on provisional Application No. 60/360,011 filed on Feb. 28, 2002, and on Japanese Application No. 2001-381051 filed in Japan on Dec. 14, 2001, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a rupturable plate for an inflator mounted in various kinds of vehicles to protect a passenger mainly when a vehicle receives an impact from the lateral direction of the vehicle, an inflator, and an air bag apparatus.
2. Description of Related Art
As an inflator for an inflating type safety system of an automobile, in order to optimally protect a passenger in accordance with a position of a seat in a vehicle such as a driver side, a front passenger side next to the driver side, and the like, various kinds of inflators utilizing a pressurized gas such as an air bag inflator for a driver side, an air bag inflator for a passenger side, an air bag inflator for a side collision, an inflator for a knee-bolster air bag, an inflator for an inflatable seat belt, an inflator for a tubular system, and an inflator for pretensioner and the like are known.
In these inflators, outflow of a pressurized gas from the inflator is started by breaking a rupturable plate, and an air bag is inflated and developed. However, since the rupturable plate is broken only by activation of an igniter, without using a so-called enhancer agent (transfer charge), it becomes important to increase destructibility of the rupturable plate, that is, to make the rupturable plate broken easily in view of increasing reliability in operation of the inflator.
Further, when small pieces produced by the broken rupturable plate enters the air bag, the air bag may get dirty or damaged. Therefore, it is also important to prevent such a situation.
Incidentally, as related prior art, a device for inflating a flexible container using both helium and hydrogen is disclosed in U.S. Pat. No. 5,527,066. A gas flow device for an air bag using a pressurized inert gas is disclosed in U.S. Pat. No. 5,782,486. An air bag apparatus for inflating an air bag by nitrogen or helium is disclosed in U.S. Pat. No. 3,680,886. Aside-collision inflator housing for an air bag which uses both pressurized gas and a gas generating agent is disclosed in U.S. Pat. No. 5,803,493. A pressurized gas inflator which uses argon or nitrogen as a pressurized gas is disclosed in JP-U No. 3031246 publication.
As described above, in the conventional inflators, it is required to achieve both increasing in destructibility of a rupturable plate and preventing broken pieces thereof from flowing in an air bag. However, when destructibility of a rupturable plate is increased, broken pieces are too small to be arrested, therefore, it becomes difficult to arrest such small pieces, or a manufacturing cost is increased because of a complicated arresting means for arresting the broken pieces such as a filter or the like.